Recovery of monobutyltin trichloride

Abstract

Monobutyltinchloride (“MBTC”) is recovered from an effluent vapor stream of a chemical vapor deposition coating process practiced to deposit a fluorine doped tin oxide layer over a glass ribbon. The vapor stream is condensed to a temperature to increase the ratio of MBTC to water in the liquid condensate. The condensed liquid is stored in a phase separation tank to separate the condensed liquid into at least two layers. The layers are individually removed from the phase separation tank, and the layer from the phase separation tank having a density equal to or greater than 80% the density of MBTC is further processed through a vacuum distilling operation to provide MBTC of an acceptable quality to use in the recovered MBTC in the coating process. The recovered MBTC is added to the coating precursors of the chemical deposition process.

1. A process to recover monobutyltinchloride hereinafter referred to as MBTC from an effluent vapor stream of a chemical vapor deposition process practiced to deposit a tin oxide film over surface of a heated glass article, the process comprises:
 cooling the effluent vapor stream to a temperature in the range of 50-190° Fahrenheit (“F”) to provide a cooled effluent vapor stream comprising liquid waste and mist; 
 phase separating the liquid waste; 
 removing liquid waste having a density equal to or greater than 1.02 gm/cc from the phase separated liquid waste defined as reclaimed MBTC liquid waste, and 
 distilling the reclaimed MBTC liquid waste to recover reclaimed MBTC liquid from the reclaimed MBTC liquid waste, wherein the reclaimed MBTC liquid has greater than 80 weight percent MBTC. 
 
     
     
       2. The process according to  claim 1  further comprising separating the liquid waste and the mist, wherein the effluent vapor stream further comprises methyl isobutyl ketone hereinafter referred to as MIBK, and water, and the reclaimed MBTC liquid has greater than 90 wt % MBTC, 0-5 wt % MIBK and 0-0.2 wt % water. 
     
     
       3. The process according to  claim 2  wherein the effluent vapor stream further comprises trifluoroacetic acid hereinafter also referred to as TFA and the reclaimed MBTC liquid has 95-98 percent MBTC, 0-5 percent MIBK, 0-0.2 percent water and 0-3 percent TFA. 
     
     
       4. The process according to  claim 3 , wherein the distilling of the reclaimed MBTC liquid waste to recover reclaimed MBTC liquid from the reclaimed MBTC liquid waste comprises a first distilling of the reclaimed MBTC liquid to remove water and TFA from the reclaimed MBTC liquid waste, and a second distilling to provide the reclaimed MBTC liquid. 
     
     
       5. The process according to  claim 4 , wherein the ratio of MBTC to water in the liquid waste is 9.5 to 1. 
     
     
       6. The process according to  claim 5  wherein the reclaimed MBTC liquid waste has a density equal to or greater than 1.12 gm/cc. 
     
     
       7. The process according to  claim 1 , wherein the ratio of MBTC to water in the cooled effluent stream is 9.5 to 1. 
     
     
       8. The process according to  claim 7  wherein the reclaimed MBTC liquid waste has a density equal to or greater than 1.12 gm/cc. 
     
     
       9. The process according to  claim 1  wherein the reclaimed MBTC liquid waste has a density equal to or greater than 1.12 gm/cc. 
     
     
       10. A method of applying a tin oxide coating to a heated glass article, comprising:
 mixing coating precursors comprising at least monobutyltinchloride hereinafter referred to as MBTC to provide a first coating composition; 
 moving the glass article and a coating zone relative to one another; 
 applying the first coating composition to a surface of the heated glass article; 
 withdrawing an effluent vapor stream from the coating zone; 
 cooling the effluent vapor stream to a temperature in the range of 50-190° Fahrenheit (“F”) to provide a cooled effluent vapor stream comprising liquid waste and mist; 
 phase separating the liquid waste; 
 removing liquid waste from the phase separated liquid waste having a density equal to or greater than 1.02 gm/cc to provide reclaimed MBTC liquid waste; 
 distilling the reclaimed MBTC liquid waste to recover reclaimed MBTC liquid from the reclaimed MBTC liquid waste, wherein the reclaimed MBTC liquid has greater than 80 wt % MBTC, and 
 mixing amounts of the precursors and the reclaimed MBTC liquid as needed to provide a second coating composition. 
 
     
     
       11. The method according to  claim 10  wherein the second coating composition is selected from the group of coating compositions comprising the same amounts of the precursors of the first coating composition, and different amounts of the precursors of the first coating composition. 
     
     
       12. The method according to  claim 10  wherein the effluent vapor stream further comprises methyl isobutyl ketone hereinafter referred to as MIBK and water, and the reclaimed MBTC liquid comprises greater than 90 wt % MBTC; greater than 0-5 wt % MIBK and 0-0.2 wt % water. 
     
     
       13. The method according to  claim 12  wherein the effluent vapor stream further comprises TFA and the reclaimed MBTC liquid further comprises 0-3 wt % TFA. 
     
     
       14. The method according to  claim 10 , wherein the distilling of the reclaimed MBTC liquid waste to recover reclaimed MBTC liquid comprises a first distilling of the reclaimed MBTC liquid waste, and a second distilling of the reclaimed MBTC liquid waste to provide the reclaimed MBTC liquid. 
     
     
       15. The method according to  claim 14 , wherein the ratio of MBTC to water in the cooled effluent stream is 9.5 to 1. 
     
     
       16. The method according to  claim 10  wherein the reclaimed MBTC liquid waste has a liquid density equal to or greater than 1.12 gm/cc. 
     
     
       17. The method according to  claim 16  wherein the reclaimed MBTC liquid waste has a liquid density equal to or greater than 1.62 gm/cc. 
     
     
       18. The method according to  claim 10  wherein the glass article is a flat piece of glass and at least one of the major surfaces of the glass is coated. 
     
     
       19. The method according to  claim 18  wherein the glass is a continuous glass ribbon and the coating zone is in a flat glass forming chamber; the continuous glass ribbon has a surface supported on a pool of molten metal contained in the glass forming chamber, and the at least one major surface of the glass ribbon is a major surface of the glass ribbon opposite to the supported surface of the glass ribbon.